From: Antoine Tenart <atenart@kernel.org>
Date: Mon, 15 Sep 2025 09:19:54 +0000 (+0200)
Subject: net: ipv4: make udp_v4_early_demux explicitly return drop reason
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1c7e4a618509476658bafba35fffb3a5cfb213b1;p=users%2Fhch%2Fmisc.git

net: ipv4: make udp_v4_early_demux explicitly return drop reason

udp_v4_early_demux already returns drop reasons as it either returns 0
or ip_mc_validate_source, which itself returns drop reasons. Its return
value is also already used as a drop reason itself.

Makes this explicit by making it return drop reasons.

Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250915091958.15382-2-atenart@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/include/net/udp.h b/include/net/udp.h
index eecd64097f91..059a0cee5f55 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -404,7 +404,7 @@ static inline struct sk_buff *skb_recv_udp(struct sock *sk, unsigned int flags,
 	return __skb_recv_udp(sk, flags, &off, err);
 }
 
-int udp_v4_early_demux(struct sk_buff *skb);
+enum skb_drop_reason udp_v4_early_demux(struct sk_buff *skb);
 bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst);
 int udp_err(struct sk_buff *, u32);
 int udp_abort(struct sock *sk, int err);
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index a09aca2c8567..8878e865ddf6 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -319,7 +319,7 @@ static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph,
 }
 
 int tcp_v4_early_demux(struct sk_buff *skb);
-int udp_v4_early_demux(struct sk_buff *skb);
+enum skb_drop_reason udp_v4_early_demux(struct sk_buff *skb);
 static int ip_rcv_finish_core(struct net *net,
 			      struct sk_buff *skb, struct net_device *dev,
 			      const struct sk_buff *hint)
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 0c40426628eb..85cfc32eb2cc 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2811,7 +2811,7 @@ static struct sock *__udp4_lib_demux_lookup(struct net *net,
 	return NULL;
 }
 
-int udp_v4_early_demux(struct sk_buff *skb)
+enum skb_drop_reason udp_v4_early_demux(struct sk_buff *skb)
 {
 	struct net *net = dev_net(skb->dev);
 	struct in_device *in_dev = NULL;
@@ -2825,7 +2825,7 @@ int udp_v4_early_demux(struct sk_buff *skb)
 
 	/* validate the packet */
 	if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct udphdr)))
-		return 0;
+		return SKB_NOT_DROPPED_YET;
 
 	iph = ip_hdr(skb);
 	uh = udp_hdr(skb);
@@ -2834,12 +2834,12 @@ int udp_v4_early_demux(struct sk_buff *skb)
 		in_dev = __in_dev_get_rcu(skb->dev);
 
 		if (!in_dev)
-			return 0;
+			return SKB_NOT_DROPPED_YET;
 
 		ours = ip_check_mc_rcu(in_dev, iph->daddr, iph->saddr,
 				       iph->protocol);
 		if (!ours)
-			return 0;
+			return SKB_NOT_DROPPED_YET;
 
 		sk = __udp4_lib_mcast_demux_lookup(net, uh->dest, iph->daddr,
 						   uh->source, iph->saddr,
@@ -2850,7 +2850,7 @@ int udp_v4_early_demux(struct sk_buff *skb)
 	}
 
 	if (!sk)
-		return 0;
+		return SKB_NOT_DROPPED_YET;
 
 	skb->sk = sk;
 	DEBUG_NET_WARN_ON_ONCE(sk_is_refcounted(sk));
@@ -2877,7 +2877,7 @@ int udp_v4_early_demux(struct sk_buff *skb)
 						     ip4h_dscp(iph),
 						     skb->dev, in_dev, &itag);
 	}
-	return 0;
+	return SKB_NOT_DROPPED_YET;
 }
 
 int udp_rcv(struct sk_buff *skb)